JPWO2013176051A1 - Multicast communication method, communication node device, and program - Google Patents

Abstract

The present invention is a communication node device that constitutes a communication system that performs multicasting. When data is transferred to a subordinate node along a normal distribution route, a retransmission timer is also provided to a child node of the redundant distribution route. The communication node device is characterized by sending a reception confirmation message to both the parent node of the normal distribution route and the parent node of the redundant distribution route when the data is set and received.

Description

The present invention relates to a multicast communication method, a communication node apparatus, and a program for performing multicast delivery redundantly and confirming reception in response to a network failure.

IP multicast that delivers an IP packet sent to a group (IP multicast address) by a sender to all receivers belonging to the multicast group has been studied for many years. In addition, highly reliable multicast for confirming reception has been studied as one of them. In recent years, many studies have been made on overlay multicast because of its ease of use. For example, Non-Patent Document 1 introduces representative studies thereof.

Popescu, A, et al., "A Survey of Reliable Multicast Communication", 3rd EuroNGI Conference on Next Generation InternetNetworks, May 2007

In overlay multicast, a route between multicast nodes (hereinafter simply referred to as nodes) is controlled by unicast routing. For example, an optimal route is selected by a routing protocol such as OSPF (Open Shortest Path First) defined in RFC (Request For Comment) 2328 of IETF (Internet Engineering Task Force). When a network line or node fails, OSPF advertises new link state information to the network and calculates a new route. In a large network, it may take several minutes for a new route to be set up. Meanwhile, communication may not be possible between overlay multicast nodes. When communication between nodes becomes impossible, multicast data distribution is interrupted there. There is a problem that data that has a limited time for distribution cannot be received in time.

  The present invention has been made in view of the above problems, and a multicast communication method and communication in which data can be reliably distributed within a restricted time even when a network failure occurs in overlay multicast, and a transmission node can confirm a reception state. It is an object to provide a node device and a program.

The present invention is a multicast communication method in a network composed of a plurality of communication nodes, and when data is transferred to a subordinate node along a normal distribution route, it is also retransmitted to a child node of the redundant distribution route When a timer is set and data is received, a reception confirmation message is sent to both the parent node of the normal distribution route and the parent node of the redundant distribution route.

The present invention is a communication node device that constitutes a communication system that performs multicasting. When data is transferred to a subordinate node along a normal distribution route, a retransmission timer is also provided to a child node of the redundant distribution route. When it is set and data is received, a reception confirmation message is sent to both the parent node of the normal distribution route and the parent node of the redundant distribution route.

The present invention is a multicast communication program, and when transferring data to a subordinate node along a normal distribution route to a computer, a process for setting a retransmission timer for a child node of a redundant distribution route, When receiving data, the program is characterized by executing a transmission process of sending a reception confirmation message to both the parent node of the normal distribution route and the parent node of the redundant distribution route.

  According to the present invention, data can be reliably distributed within a restricted time even in the event of a network failure in overlay multicast, and the transmission node can confirm the reception state.

FIG. 1 is a functional configuration diagram of a communication node device according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration example of a network for carrying out the present invention. FIG. 3 is a diagram illustrating an example of a distribution tree. FIG. 4 is a diagram for explaining a normal communication sequence. FIG. 5 is a diagram for explaining a normal communication sequence. FIG. 6 is a diagram for explaining a normal communication sequence. FIG. 7 is a diagram for explaining a normal communication sequence. FIG. 8 is a diagram for explaining a normal communication sequence. FIG. 9 is a diagram for explaining a normal communication sequence. FIG. 10 is a diagram for explaining a normal communication sequence. FIG. 11 is a diagram for explaining a communication sequence at the time of failure. FIG. 12 is a diagram for explaining a communication sequence at the time of failure. FIG. 13 is a diagram for explaining a communication sequence at the time of failure. FIG. 14 is a diagram for explaining a communication sequence at the time of failure. FIG. 15 is a diagram for explaining a communication sequence at the time of failure. FIG. 16 is a diagram for explaining a communication sequence at the time of failure. FIG. 17 is a diagram for explaining a communication sequence at the time of failure. FIG. 18 is a diagram for explaining a communication sequence at the time of failure. FIG. 19 is a diagram for explaining a communication sequence at the time of failure.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of a communication node device according to an embodiment of the present invention. The communication node device according to the embodiment of the present invention includes a packet reception unit 901, a packet transmission unit 902, a data processing unit 903, an ACK creation unit 904, a data transfer unit 906, a retransmission management unit 905, a distribution route table 907, and a retransmission management table. 908.

  In the delivery route table 907, parent nodes and child nodes are registered in advance for normal and redundant delivery routes. The distribution route will be described later.

  The retransmission management table 908 includes retransmission data information such as a retransmission timer for the node that transmitted the data, ACK (reception confirmation message) information received from other nodes, and data reception information (information of the transmission source node) regarding the received data. Etc.) are stored.

  The packet receiving unit 901 receives a packet (data or ACK) from another communication node device. When receiving data, the packet receiving unit 901 passes the received data to the data processing unit 903. When ACK is received, it is passed to the retransmission management section 905.

  The packet transmission unit 902 transmits the requested data or ACK to another communication node.

  The data processing unit 903 passes the data received from the packet receiving unit 901 to the data transfer unit 906 and issues an ACK creation request to the ACK creation unit 904.

  Based on the delivery route table 907, the ACK creation unit 904 determines a node to send an ACK and creates an ACK. The ACK destination is the parent node (normal system and redundant system) registered in the distribution route table 907. The ACK creation unit 904 obtains the data transmission source node from the retransmission management table 908 at the time of ACK creation, and adds ACK transfer information when the transmission source node is the parent node of the redundant distribution route. The ACK transfer information includes information on the parent node of the redundant delivery route that is the transmission source and the parent node of the normal delivery route. When the ACK is created, the packet transmission unit 902 is requested to transmit.

  The data transfer unit 906 acquires the distribution route information registered in the distribution route table 907 and determines which node to transfer. When determining the transfer destination node, the data transfer unit 906 requests the packet transmission unit 902 to transmit data. Thereafter, the retransmission management unit 905 is requested to set a data retransmission timer.

  In response to the request from the data transfer unit 906, the retransmission management unit 905 sets a retransmission timer for each receiving node. The retransmission timer is set for the normal and redundant child nodes when data is transferred to the subordinate nodes along the normal distribution route. Also, the ACK information from the packet receiving unit 901 is recorded in the retransmission management table 908, and the corresponding retransmission timer is canceled. Further, when ACK transfer information is added to the ACK from the packet receiving unit 901, if the parent node of the source redundant distribution route indicated by the ACK transfer information matches itself, the ACK transfer information is The packet transmission unit 902 is requested to transfer ACK to the parent node of the normal distribution route shown.

  FIG. 2 shows a configuration example of a network for carrying out the present invention. In the example, there are 10 communication node devices (hereinafter simply referred to as nodes) 101, 102, 111, 112, 121, 122, 131, 132, 141, 142. Nodes 101 and 102, 111 and 112, 121 and 122, 131 and 132, and 141 and 142 are connected to the same LAN (Local Area Network). Each LAN is connected in a ring shape by five routers 201-205.

  All nodes belong to the same multicast group (hereinafter simply referred to as group), and multicast data (hereinafter simply referred to as data) is distributed by overlay multicast. Here, the node 101 is called an origin node that generates data, and the other nodes are called receiving nodes that receive data. The nodes 111, 121, 131, and 141 serve as transfer nodes that transfer data onto each LAN.

  Data distribution from the node 101 is performed along the distribution tree of FIG. The solid line in FIG. 3 is a normal transfer path, and the dotted line is a redundant transfer path used when the upper path is disconnected. The normal transfer path and the redundant transfer path are set so that the links do not overlap. For example, for the node 121, different links are used for the route from the node 101 to 121 and the route from the node 111 to 121. FIG. 4 is an example of route setting between nodes in an actual network. The path 302 between the nodes 101 and 121 passes through a different link from the path 401 between the nodes 111 and 121, so that both sides do not become disconnected at the same time for a single link failure.

(1) Normal Transfer Sequence First, a normal data transfer procedure in which no failure has occurred will be described with reference to FIGS. The arrow line in the figure indicates the flow of packets (data or ACK) between nodes, the solid line arrow indicates transmission by IP unicast, and the dotted line arrow indicates transmission by IP multicast.

  Each data can be uniquely identified by the origin node 101 adding a sequence number. ACK contains information of (origin node ID, group ID, sequence number) and can identify which data is the reception notification.

  In the present invention, two types of ACK for notifying reception are defined. One is ACK (Complete) and the other is ACK (Pending). ACK (Complete) is a data transfer source when a receiving node that does not transfer any more receives data, or when the transferring node receives ACK (Complete) from all receiving nodes that are responsible for the transfer. It is sent back to the node (parent node on the distribution route). When the transfer node receives data, ACK (Pending) is returned to the data transfer source node in order to notify that it has received the data before performing the transfer.

  In FIG. 5, when data to be transmitted is generated, the origin node 101 transmits to all receiving nodes on the local LAN using IP multicast on the local LAN (501). Furthermore, data is transmitted to forwarding nodes 111 and 121 of different LANs using IP unicast (511 and 521). The node 101 sets a retransmission timer for the nodes 111, 121, and 102 after transmission.

  In FIG. 6, the node 102 that has received the data transmitted by IP multicast on the LAN returns an ACK (Complete) indicating that the data has been received to the node 101 by IP unicast (502). When the node 101 receives the ACK from the node 102, the node 101 cancels the retransmission timer to the node 102.

  The nodes 111 and 121 that have received data from the origin node 101 transmit ACK (Pending) to the node 101 (512 and 513). Further, the nodes 111 and 121 similarly transmit ACK (Pending) to each other, which is the parent of the redundant transfer path (513 and 523). When receiving the ACK from the nodes 111 and 121, the node 101 cancels the retransmission timer for the nodes 111 and 121. The nodes 111 and 121 record the ACK (513, 523) received from each node.

  In FIG. 7, the node 111 transfers the received data to the receiving node 112 on its own LAN using IP multicast (514). Furthermore, it transfers by IP unicast to the transfer node 131 on a different LAN (531). The node 111 sets a retransmission timer for the nodes 112 and 131. Since the node 121 has already received ACK (523) for the data, no retransmission timer is set.

  The node 121 transfers the received data to the receiving node 122 on its own LAN using IP multicast (524). Further, the data is transferred to the transfer node 141 on a different LAN by IP unicast (541). The node 121 sets a retransmission timer for the nodes 122 and 141. Note that since the node 111 has already received ACK (513) for the data, no retransmission timer is set.

  In FIG. 8, after receiving the data, the node 112 returns ACK (Complete) to the node 111 (515). When the node 111 receives the ACK, the node 111 cancels the retransmission timer for the node 112.

  After receiving the data, the node 131 returns ACK (Pending) to the node 111 (532). When node 111 receives the ACK, it cancels the retransmission timer to node 131. The node 131 further transmits ACK (Pending) to the node 141 which is the parent node of the redundant transfer path (533). The node 141 records the received ACK.

  After receiving the data, the node 122 returns ACK (Complete) to the node 121 (525). When the node 121 receives the ACK, the node 121 cancels the retransmission timer for the node 122.

  When receiving the data, the node 141 returns ACK (Pending) to the node 121 (542). When node 121 receives the ACK, node 121 cancels the retransmission timer to node 141. The node 141 further transmits ACK (Pending) to the node 131 which is the parent node of the redundant transfer path (543). The node 131 records the received ACK.

  In FIG. 9, the node 131 transfers the received data to the receiving node 132 on its own LAN using IP multicast (534), and sets a retransmission timer for the node 132. Similarly, the node 141 transfers the received data to the receiving node 142 on its own LAN using the IP multicast (544), and sets a retransmission timer for the node 142.

  In FIG. 10, when receiving the data, the node 132 returns ACK (Complete) to the node 131 (535). When the node 131 receives the ACK, the node 131 cancels the retransmission timer for the node 132. Since the node 131 has received ACK (Complete) from all receiving nodes under the transfer path, the node 131 transmits ACK (Complete) to the node 111 (536). When the node 111 receives ACK (Compete) from the node 131, it similarly receives ACK (Complete) from all receiving nodes under the transfer path, and therefore transmits ACK (Complete) to the node 101 (516).

  When the node 142 receives the data, it returns an ACK (Complete) to the node 141 (545). When the node 141 receives the ACK, the node 141 cancels the retransmission timer for the node 142. Since the node 141 has received ACK (Complete) from all receiving nodes under the transfer path, the node 141 transmits ACK (Complete) to the node 121 (546). When the node 121 receives ACK (Compete) from the node 141, it similarly receives ACK (Complete) from all receiving nodes under the transfer path, and therefore transmits ACK (Complete) to the node 101 (526). The node 101 receives ACK (Complete) from all receiving nodes under the transfer path, and confirms that all receiving nodes in the network have received data.

(2) Transfer Sequence at Link Failure Next, a transfer sequence when a link failure occurs between the routers 201 and 203 and communication between the nodes 101 and 121 is interrupted will be described with reference to FIGS.

  In FIG. 11, the origin node 101 transmits data to the receiving node 102 on its own LAN, and the nodes 111 and 121 on different LANs (6101, 6201, 6301). However, due to a link failure, the data 6201 sent to the node 121 is discarded by the router 201 and does not reach the node 121. The node 101 sets a retransmission timer for the nodes 111, 121, and 102.

  In FIG. 12, the node 102 responds to the node 101 with ACK (Complete) (6102). When node 101 receives the ACK, node 101 cancels the retransmission timer to node 102. The node 111 returns an ACK (Pending) response to the nodes 101 and 121 (6302 and 6303). When node 101 receives the ACK, node 101 cancels the retransmission timer to node 111. The node 121 records that the ACK is received from the node 111 which is the parent node of the redundant system for the data which has not been received.

  In FIG. 13, the node 111 transfers data to the receiving node 112 on its own LAN using IP multicast (6305). Further, data transfer is also performed to the transfer node 131 on a different LAN by IP unicast (6304). The node 111 sets a retransmission timer for the nodes 112 and 131. Furthermore, a retransmission timer is also set for the node 121 which is a redundant child node.

  In FIG. 14, the node 112 responds with ACK (Complete) to the node 111 (6306). When node 111 receives the ACK, node 111 cancels the retransmission timer for node 112. The node 131 returns ACK (Pending) to the node 111 (6307). Furthermore, ACK (Pending) is also transmitted to the node 141 which is a child node of the redundant system (6308).

  The node 131 transfers the data to the node 132 on its own LAN by IP multicast (6309). The node 131 sets a retransmission timer for the node 132 and the node 141 which is a redundant child node.

  When the node 111 receives the ACK from the node 131, the node 111 cancels the retransmission timer to the node 131.

  The node 141 records that the ACK of the data that has not been received has been received from the node 131 that is the parent node of the redundant system.

  In FIG. 15, the node 101 retransmits the data to the node 121 by firing a retransmission timer to the node 121 (6202). However, this data is also discarded due to a failure and does not reach the node 121.

  The node 111 also fires the retransmission timer to the node 121 and transmits data to the node 121 (6312).

  The node 132 transmits ACK (Complete) to the node 131 (6310). When the node 131 receives the ACK, it receives the ACK (Complete) from all subordinate receiving nodes, and therefore transmits the ACK (Complete) to the node 111 (6311).

  In FIG. 16, when receiving data from the node 111, the node 121 transmits ACK (Pending) to the normal parent node 101 and the redundant parent node 111 (6203 and 6204). . Since the node 121 has received data from the redundant parent node 111 instead of the normal parent node 101, the node that is the data reception source node (redundant parent node) in response to the ACK (Pending) to the node 111 111 and the information of the node 101 which is a normal parent node are added. The 6203 ACK transmitted to the node 101 is discarded due to a failure and does not reach the node 101.

  The node 111 receives ACK (Pending) from the node 121. When it is confirmed that the ACK contains its own information as the data reception source node (redundant parent node), the node 111 transfers the ACK to the node 101 which is the normal parent node of the node 121 (6205). ).

  When the node 101 receives the ACK (Pending) of the node 121 transferred from the node 111, the node 101 cancels the retransmission timer to the node 121.

  In FIG. 17, the node 121 transfers the received data to the receiving node 122 on its own LAN by IP multicast (6206). Further, the data is transferred to the node 141 by IP unicast (6207). The node 121 sets a retransmission timer for the node 122 and the node 141.

  In FIG. 18, when receiving data, the node 122 transmits ACK (Complete) to the node 121 (6208). When the node 121 receives the ACK, the node 121 cancels the retransmission timer to the node 122.

  The node 141 also transmits ACK (Pending) to the node 121 and the node 131 which is the redundant parent node (6209, 6210). When the node 131 receives the ACK from the node 141, the node 131 cancels the retransmission timer to the node 141. The node 141 transfers the data to the receiving node 142 on its own LAN using IP multicast (6211).

  In FIG. 19, when the node 142 receives data, the node 142 responds with ACK (Complete) to the node 141 (6212). When the node 141 receives the ACK, the node 141 confirms that the ACK (Complete) has been received from all subordinate recipients, and transmits ACK (Complete) to the node 121 and the node 131 which is the redundant parent node (6213). 6214).

  The node 121 confirms that ACK (Complete) has been received from all subordinate receiving nodes, and transmits ACK (Complete) to the normal parent node 101 and the redundant parent node 111 (6215, 6216). Since the node 121 receives the data from the redundant parent node 111 instead of the normal parent node 101, the node 121 also receives the ACK (Complete) to the node 111 from the node 111 that is the data receiving node. The information of the node 101 which is the normal parent node is added.

  The ACK (6215) to the node 101 is discarded due to a failure and does not reach the node 101.

  The node 111 receives ACK (Complete) from the node 121. When it is confirmed that the information added to the ACK includes its own information as the data receiving node, the node 111 transfers the ACK to the node 101 which is the normal parent node of the node 121 (6217). .

  When the node 101 receives the ACK (Complete) of the node 121 transferred from the node 111, it confirms that the ACK (Complete) has been received from all the receiving nodes under its control, and all the receiving nodes in the network have received it normally. Recognize that.

  As described above, according to the present invention, even when a network failure occurs in overlay multicast, data is distributed from the redundant parent node, and delivery is confirmed via the redundant parent node to ensure that the data is within the restricted time. And the transmission node can confirm the reception state.

  The communication node device according to the above-described embodiment of the present invention may be realized by a CPU (Central Processing Unit) reading and executing an operation program or the like stored in a storage unit, or configured by hardware. May be. Only some functions of the above-described embodiments can be realized by a computer program.

  Moreover, although a part or all of said embodiment can be described also as the following additional remarks, it is not restricted to the following.

(Supplementary note 1) A multicast communication method in a network composed of a plurality of communication nodes,
When data is transferred to a subordinate node along the normal delivery route, a retransmission timer is set for the child node of the redundant delivery route,
A multicast communication method characterized by sending a reception confirmation message to both a parent node of a normal distribution route and a parent node of a redundant distribution route when data is received.

(Appendix 2)
When data is received from a parent node of a redundant delivery route, information on the parent node of the redundant delivery route that is the transmission source and the parent node of the normal delivery route is added to the reception confirmation message,
When the reception confirmation message with the information of the parent node of the redundant distribution route that is the transmission source and the parent node of the normal distribution route is received, the redundant system that is the transmission source that is added to the reception confirmation message. The multicast communication method according to appendix 1, wherein if the transmission path matches the parent node of the distribution route, the reception confirmation message is transferred to the parent node of the normal distribution path added to the reception confirmation message.

(Appendix 3)
If the node itself is a forwarding node in the distribution route, when receiving data, the first reception confirmation message is sent to both the parent node of the normal distribution route and the parent node of the redundant distribution route,
If it is a terminal node in the distribution route, when receiving data, it sends a second receipt confirmation message to the normal parent node,
Note that when the second receipt confirmation message is received from all the child nodes of its own delivery route, the second receipt confirmation message is sent to the parent nodes of both the normal delivery route and the redundant delivery route. The multicast communication method according to 1 or appendix 2.

(Appendix 4)
A communication node device constituting a communication system that performs multicasting,
When data is transferred to a subordinate node along the normal delivery route, a retransmission timer is set for the child node of the redundant delivery route,
A communication node device that, when receiving data, sends a reception confirmation message to both a parent node of a normal distribution route and a parent node of a redundant distribution route.

(Appendix 5)
When data is received from a parent node of a redundant delivery route, information on the parent node of the redundant delivery route that is the transmission source and the parent node of the normal delivery route is added to the reception confirmation message,
When the reception confirmation message with the information of the parent node of the redundant distribution route that is the transmission source and the parent node of the normal distribution route is received, the redundant system that is the transmission source that is added to the reception confirmation message. The communication node device according to appendix 4, wherein if the parent node of the distribution route matches, the reception confirmation message is transferred to the parent node of the normal distribution route added to the reception confirmation message.

(Appendix 6)
If the node itself is a forwarding node in the distribution route, when receiving data, the first reception confirmation message is sent to both the parent node of the normal distribution route and the parent node of the redundant distribution route,
If it is a terminal node in the distribution route, when receiving data, it sends a second receipt confirmation message to the normal parent node,
Note that when the second receipt confirmation message is received from all the child nodes of its own delivery route, the second receipt confirmation message is sent to the parent nodes of both the normal delivery route and the redundant delivery route. 4. The communication node device according to 4 or appendix 5.

(Appendix 7)
A multicast communication program,
On the computer,
When data is transferred to a subordinate node along the normal delivery route, a process for setting a retransmission timer for the child node of the redundant delivery route,
When receiving data, a transmission process that sends a reception confirmation message to both the parent node of the normal distribution route and the parent node of the redundant distribution route,
A program characterized by having executed.

(Appendix 8)
In the computer,
When receiving data from a parent node of a redundant delivery route, a process of adding information on the parent node of the redundant delivery route that is the transmission source and the parent node of the normal delivery route to the reception confirmation message;
When the reception confirmation message with the information of the parent node of the redundant distribution route that is the transmission source and the parent node of the normal distribution route is received, the redundant system that is the transmission source that is added to the reception confirmation message. A process for transferring the reception confirmation message to the parent node of the normal distribution route added to the reception confirmation message if it matches the parent node of the distribution route;
The program according to appendix 7, wherein the program is further executed.

(Appendix 9)
In the computer,
A process of sending a first reception confirmation message to both the parent node of the normal distribution route and the parent node of the redundant distribution route when data is received when it is a forwarding node in the distribution route;
A process of sending a second reception confirmation message to the normal parent node when data is received when the terminal node is a terminal node in the distribution route;
A process of sending the second reception confirmation message to the parent nodes of both the normal distribution path and the redundant distribution path when the second reception confirmation message is received from all the child nodes of its own distribution path;
The program according to appendix 7 or appendix 8, wherein the program is further executed.

  Although the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea.

  This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2012-115398 for which it applied on May 21, 2012, and takes in those the indications of all here.

101, 102, 111, 112, 131, 132, 141, 142 Node 201-205 Router

Claims (9)

A multicast communication method in a network composed of a plurality of communication nodes,
When data is transferred to a subordinate node along the normal delivery route, a retransmission timer is set for the child node of the redundant delivery route,
A multicast communication method characterized by sending a reception confirmation message to both a parent node of a normal distribution route and a parent node of a redundant distribution route when data is received. When data is received from a parent node of a redundant delivery route, information on the parent node of the redundant delivery route that is the transmission source and the parent node of the normal delivery route is added to the reception confirmation message,
When the reception confirmation message with the information of the parent node of the redundant distribution route that is the transmission source and the parent node of the normal distribution route is received, the redundant system that is the transmission source that is added to the reception confirmation message. 2. The multicast communication method according to claim 1, wherein if the transmission path matches the parent node of the distribution path, the reception confirmation message is transferred to the parent node of the normal distribution path added to the reception confirmation message. If the node itself is a forwarding node in the distribution route, when receiving data, the first reception confirmation message is sent to both the parent node of the normal distribution route and the parent node of the redundant distribution route,
If it is a terminal node in the distribution route, when receiving data, it sends a second receipt confirmation message to the normal parent node,
When the second reception confirmation message is received from all the child nodes of its own distribution route, the second reception confirmation message is sent to the parent nodes of both the normal distribution route and the redundant distribution route. The multicast communication method according to claim 1 or 2. A communication node device constituting a communication system that performs multicasting,
When data is transferred to a subordinate node along the normal delivery route, a retransmission timer is set for the child node of the redundant delivery route,
A communication node device that, when receiving data, sends a reception confirmation message to both a parent node of a normal distribution route and a parent node of a redundant distribution route. When data is received from a parent node of a redundant delivery route, information on the parent node of the redundant delivery route that is the transmission source and the parent node of the normal delivery route is added to the reception confirmation message,
When the reception confirmation message with the information of the parent node of the redundant distribution route that is the transmission source and the parent node of the normal distribution route is received, the redundant system that is the transmission source that is added to the reception confirmation message. 5. The communication node device according to claim 4, wherein if it matches the parent node of the distribution route, the reception confirmation message is transferred to the parent node of the normal distribution route added to the reception confirmation message. If the node itself is a forwarding node in the distribution route, when receiving data, the first reception confirmation message is sent to both the parent node of the normal distribution route and the parent node of the redundant distribution route,
If it is a terminal node in the distribution route, when receiving data, it sends a second receipt confirmation message to the normal parent node,
When the second reception confirmation message is received from all the child nodes of its own distribution route, the second reception confirmation message is sent to the parent nodes of both the normal distribution route and the redundant distribution route. The communication node device according to claim 4 or 5. A multicast communication program,
On the computer,
When data is transferred to a subordinate node along the normal delivery route, a process for setting a retransmission timer for the child node of the redundant delivery route,
When receiving data, a transmission process that sends a reception confirmation message to both the parent node of the normal distribution route and the parent node of the redundant distribution route,
A program characterized by having executed. In the computer,
When receiving data from a parent node of a redundant delivery route, a process of adding information on the parent node of the redundant delivery route that is the transmission source and the parent node of the normal delivery route to the reception confirmation message;
When the reception confirmation message with the information of the parent node of the redundant distribution route that is the transmission source and the parent node of the normal distribution route is received, the redundant system that is the transmission source that is added to the reception confirmation message. A process for transferring the reception confirmation message to the parent node of the normal distribution route added to the reception confirmation message if it matches the parent node of the distribution route;
8. The program according to claim 7, further comprising: In the computer,
A process of sending a first reception confirmation message to both the parent node of the normal distribution route and the parent node of the redundant distribution route when data is received when it is a forwarding node in the distribution route;
A process of sending a second reception confirmation message to the normal parent node when data is received when the terminal node is a terminal node in the distribution route;
A process of sending the second reception confirmation message to the parent nodes of both the normal distribution path and the redundant distribution path when the second reception confirmation message is received from all the child nodes of its own distribution path;
The program according to claim 7 or 8, further comprising:

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